Improvement in the order of



UNITED STATES PATENT OFFICE.

s. W. PINGREE, OF METHUEN, MASSACHUSETTS.

lMPROVEMENT IN THE ORDER OF APPLYING TAN-LIQUOR T0 HIDES.

Specification forming part of Letters Patent No. 15,896, dated October14, 1856.

To all whom it may concern:

Beit known that I, SAMUEL W. PINGREE, of Methuen, in the county of Essexand State of Massachusetts, have invented a new and useful Improvementin Tanning Hides and Skins; and I do hereby declare that the same isfully described in the following specification. I

My invention will be found to be especially useful in tanning hides andskins with their hair upon them, and so that when said hides or skinsare tanned the hair with the epidermis shall remain on the leather; andin order to' facilitate the process of tanning the hide or skin after ithas been washed and beamed and the surplus flesh removed from the innersurface of the corium in the ordinary way, the corium or inner layer ofthe skin, and so much of the middle layer as may be necessary to reducethe skin to an equal thickness throughout, may be skived or removed fromthe remainder of the skin or hide. When the hide is reduced to an eventhickness all it parts will be tanned equally in the same time.

In carrying out my invention, after the hides have been prepared in theusual way, or in manner as above described, I proceed as follows intanning, say, twenty-five hides: I add to five hogsheads of water onepeek of lime, five pounds of Sal-soda, and twelve pounds of sodaash 5or, instead of the sal-soda and soda-ash,

fifteen pounds of soda-ash may be used. The hides are to be placed andallowed to remain in this solution about twelve (or more) hours, but notlong enough to start or loosen the hair. Next, they are to be rinsed inwater and subsequently steeped in another solution composed of fivehogsheads of water, one bushel muriate of soda, and twelve pounds ofsuphuric acid. In this solution they should be suffered to remaintwenty-four hours, or more, according to the thickness of the hide, andwhile in such solution the hides should be well stirred, so that theacid may actupon the glutinous matter and neutralize the alkaliremaining in them, and prepare them for the reception of thetanning-liquor. This assists the penetration of the tanning liquor intothe hides. Next, the hides are to be immersed for three days in asolution composed of five hogsheads of water and fifty pounds of Bombaycatechu. This solution not only partially tans the hide, but has aneffect to toughen it upon the grain side, so that when the hide is nextsubjected to the action of the bark-liquor such may not weaken the outerside or grained surface of the hide. Next, steep the hides in a strongbark-liquor, and suffer them to remain in the same ten or twelve days. Next, add to the bark-liquor fifty pounds of sumac and twenty-five poundsof ground alum, and suffer the hides to remain one week longer in suchsolution, they being stirred occasionally in the meantime. Thiscompletes the process.

The object of using sumac and alum at the stage of the process abovedescribed is to soften the partly-tanned skins or to retain them in asoft state, so that they may be pliable when the tanning process iscompleted. The alum toughens the hide.

I do not claim the separate use of any of the chemical materialshereinbefore mentioned for the process of tanning, as I am aware thatall of them have been before employed, and particularly I do not claimthe neutralization of the alkali by the use of sulphuric acidpreparatory to the introduction of the hides into the tanning-liquor butWhat I do claim as an improvement is The use of the catcchu and thesumac and alum, with reference to the application of the bark or strongtanning-liquor, as stated, and so as to produce effects as set forth andin the order as specified, when the hide is tanned with the hair on it.

In testimony whereof I have hereunto setmy signature this 19th day ofJune, A. D. 1856. SAMUEL W. PINGREE.

Witnesses R. H. EDDY, F. P. HALE, Jr.

